/*
 * Copyright (C) 2014 The Guava Authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
 * in compliance with the License. You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software distributed under the License
 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
 * or implied. See the License for the specific language governing permissions and limitations under
 * the License.
 */

package com.google.common.io;

import com.google.caliper.BeforeExperiment;
import com.google.caliper.Benchmark;
import com.google.caliper.Param;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.StringReader;
import java.io.StringWriter;
import java.util.Random;

/**
 * Benchmark for {@code BaseEncoding} performance.
 */
public class BaseEncodingBenchmark
{
    private static final int INPUTS_COUNT = 0x1000;
    private static final int INPUTS_MASK = 0xFFF;

    enum EncodingOption
    {
        BASE64(BaseEncoding.base64()),
        BASE64_URL(BaseEncoding.base64Url()),
        BASE32(BaseEncoding.base32()),
        BASE32_HEX(BaseEncoding.base32Hex()),
        BASE16(BaseEncoding.base16());

        final BaseEncoding encoding;

        EncodingOption(BaseEncoding encoding)
        {
            this.encoding = encoding;
        }
    }

    @Param
    EncodingOption encoding;

    @Param({"10", "100", "10000"})
    int n;

    private final byte[][] encodingInputs = new byte[INPUTS_COUNT][];
    private final String[] decodingInputs = new String[INPUTS_COUNT];

    @BeforeExperiment
    public void setUp()
    {
        Random rng = new Random();
        for (int i = 0; i < encodingInputs.length; i++)
        {
            encodingInputs[i] = new byte[n];
            rng.nextBytes(encodingInputs[i]);
            decodingInputs[i] = encoding.encoding.encode(encodingInputs[i]);
        }
    }

    @Benchmark
    public int encode(int reps)
    {
        int tmp = 0;
        for (int i = 0; i < reps; i++)
        {
            tmp += System.identityHashCode(encoding.encoding.encode(encodingInputs[i & INPUTS_MASK]));
        }
        return tmp;
    }

    @Benchmark
    public int decode(int reps)
    {
        int tmp = 0;
        for (int i = 0; i < reps; i++)
        {
            tmp += System.identityHashCode(encoding.encoding.decode(decodingInputs[i & INPUTS_MASK]));
        }
        return tmp;
    }

    @Benchmark
    public int encodingStream(int reps) throws IOException
    {
        int tmp = 0;
        for (int i = 0; i < reps; i++)
        {
            StringWriter target = new StringWriter(2 * n);
            OutputStream encodingStream = encoding.encoding.encodingStream(target);
            encodingStream.write(encodingInputs[i & INPUTS_MASK]);
            encodingStream.close();
            tmp += target.getBuffer().length();
        }
        return tmp;
    }

    @Benchmark
    public int decodingStream(int reps) throws IOException
    {
        int tmp = 0;
        byte[] target = new byte[n];
        for (int i = 0; i < reps; i++)
        {
            StringReader source = new StringReader(decodingInputs[i & INPUTS_MASK]);
            InputStream decodingStream = encoding.encoding.decodingStream(source);
            decodingStream.read(target);
            decodingStream.close();
            tmp += target[0];
        }
        return tmp;
    }
}
